Unexpected Deformation Behavior in Mesoscale Model with Two Distinct Harmonic Bond Stiffnesses

Hello LAMMPS community,

I am currently working on developing a mesoscale model of a network containing two different types of harmonic bonds, each with their own distinct stiffness values. The first bond type is significantly stiffer than the second (K1 > 10*K2). I have been using the “fix deform” command to apply deformation to the system.

However, I have encountered an unexpected issue: the stiffer bonds (K1) are deforming more than the softer bonds (K2), which seems counterintuitive. I would have expected the softer bonds to deform more readily under the applied deformation.

Does anyone have any insights or suggestions as to why this might be happening? I would greatly appreciate any advice or assistance that you could provide.

Thank you in advance for your help!

It is very difficult to discuss these kind of issues on such a general level. There are just too many degrees of freedom and there also is a possibility that you have made a mistake somewhere.

It would be much easier to discuss, if you could provide a small and fast to run input deck that just demonstrates the issue (and has all unrelated commands removed). Please remember to also let us know what version of LAMMPS you are using and what platform you are running on with what command line.